1// SPDX-License-Identifier: GPL-2.0
2/*
3 *
4 * A test for the patch "Allow compaction of unevictable pages".
5 * With this patch we should be able to allocate at least 1/4
6 * of RAM in huge pages. Without the patch much less is
7 * allocated.
8 */
9
10#include <stdio.h>
11#include <stdlib.h>
12#include <sys/mman.h>
13#include <sys/resource.h>
14#include <fcntl.h>
15#include <errno.h>
16#include <unistd.h>
17#include <string.h>
18
19#include "../kselftest.h"
20
21#define MAP_SIZE_MB 100
22#define MAP_SIZE (MAP_SIZE_MB * 1024 * 1024)
23
24struct map_list {
25 void *map;
26 struct map_list *next;
27};
28
29int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize)
30{
31 char buffer[256] = {0};
32 char *cmd = "cat /proc/meminfo | grep -i memfree | grep -o '[0-9]*'";
33 FILE *cmdfile = popen(cmd, "r");
34
35 if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
36 ksft_print_msg(msg: "Failed to read meminfo: %s\n", strerror(errno));
37 return -1;
38 }
39
40 pclose(cmdfile);
41
42 *memfree = atoll(buffer);
43 cmd = "cat /proc/meminfo | grep -i hugepagesize | grep -o '[0-9]*'";
44 cmdfile = popen(cmd, "r");
45
46 if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
47 ksft_print_msg(msg: "Failed to read meminfo: %s\n", strerror(errno));
48 return -1;
49 }
50
51 pclose(cmdfile);
52 *hugepagesize = atoll(buffer);
53
54 return 0;
55}
56
57int prereq(void)
58{
59 char allowed;
60 int fd;
61
62 fd = open("/proc/sys/vm/compact_unevictable_allowed",
63 O_RDONLY | O_NONBLOCK);
64 if (fd < 0) {
65 ksft_print_msg(msg: "Failed to open /proc/sys/vm/compact_unevictable_allowed: %s\n",
66 strerror(errno));
67 return -1;
68 }
69
70 if (read(fd, &allowed, sizeof(char)) != sizeof(char)) {
71 ksft_print_msg(msg: "Failed to read from /proc/sys/vm/compact_unevictable_allowed: %s\n",
72 strerror(errno));
73 close(fd);
74 return -1;
75 }
76
77 close(fd);
78 if (allowed == '1')
79 return 0;
80
81 ksft_print_msg(msg: "Compaction isn't allowed\n");
82 return -1;
83}
84
85int check_compaction(unsigned long mem_free, unsigned int hugepage_size)
86{
87 int fd, ret = -1;
88 int compaction_index = 0;
89 char initial_nr_hugepages[10] = {0};
90 char nr_hugepages[10] = {0};
91
92 /* We want to test with 80% of available memory. Else, OOM killer comes
93 in to play */
94 mem_free = mem_free * 0.8;
95
96 fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
97 if (fd < 0) {
98 ksft_print_msg(msg: "Failed to open /proc/sys/vm/nr_hugepages: %s\n",
99 strerror(errno));
100 ret = -1;
101 goto out;
102 }
103
104 if (read(fd, initial_nr_hugepages, sizeof(initial_nr_hugepages)) <= 0) {
105 ksft_print_msg(msg: "Failed to read from /proc/sys/vm/nr_hugepages: %s\n",
106 strerror(errno));
107 goto close_fd;
108 }
109
110 /* Start with the initial condition of 0 huge pages*/
111 if (write(fd, "0", sizeof(char)) != sizeof(char)) {
112 ksft_print_msg(msg: "Failed to write 0 to /proc/sys/vm/nr_hugepages: %s\n",
113 strerror(errno));
114 goto close_fd;
115 }
116
117 lseek(fd, 0, SEEK_SET);
118
119 /* Request a large number of huge pages. The Kernel will allocate
120 as much as it can */
121 if (write(fd, "100000", (6*sizeof(char))) != (6*sizeof(char))) {
122 ksft_print_msg(msg: "Failed to write 100000 to /proc/sys/vm/nr_hugepages: %s\n",
123 strerror(errno));
124 goto close_fd;
125 }
126
127 lseek(fd, 0, SEEK_SET);
128
129 if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
130 ksft_print_msg(msg: "Failed to re-read from /proc/sys/vm/nr_hugepages: %s\n",
131 strerror(errno));
132 goto close_fd;
133 }
134
135 /* We should have been able to request at least 1/3 rd of the memory in
136 huge pages */
137 compaction_index = mem_free/(atoi(nr_hugepages) * hugepage_size);
138
139 lseek(fd, 0, SEEK_SET);
140
141 if (write(fd, initial_nr_hugepages, strlen(initial_nr_hugepages))
142 != strlen(initial_nr_hugepages)) {
143 ksft_print_msg(msg: "Failed to write value to /proc/sys/vm/nr_hugepages: %s\n",
144 strerror(errno));
145 goto close_fd;
146 }
147
148 ksft_print_msg(msg: "Number of huge pages allocated = %d\n",
149 atoi(nr_hugepages));
150
151 if (compaction_index > 3) {
152 ksft_print_msg(msg: "ERROR: Less that 1/%d of memory is available\n"
153 "as huge pages\n", compaction_index);
154 goto close_fd;
155 }
156
157 ret = 0;
158
159 close_fd:
160 close(fd);
161 out:
162 ksft_test_result(ret == 0, "check_compaction\n");
163 return ret;
164}
165
166
167int main(int argc, char **argv)
168{
169 struct rlimit lim;
170 struct map_list *list = NULL, *entry;
171 size_t page_size, i;
172 void *map = NULL;
173 unsigned long mem_free = 0;
174 unsigned long hugepage_size = 0;
175 long mem_fragmentable_MB = 0;
176
177 ksft_print_header();
178
179 if (prereq() || geteuid())
180 return ksft_exit_skip(msg: "Prerequisites unsatisfied\n");
181
182 ksft_set_plan(plan: 1);
183
184 lim.rlim_cur = RLIM_INFINITY;
185 lim.rlim_max = RLIM_INFINITY;
186 if (setrlimit(RLIMIT_MEMLOCK, &lim))
187 ksft_exit_fail_msg(msg: "Failed to set rlimit: %s\n", strerror(errno));
188
189 page_size = getpagesize();
190
191 if (read_memory_info(memfree: &mem_free, hugepagesize: &hugepage_size) != 0)
192 ksft_exit_fail_msg(msg: "Failed to get meminfo\n");
193
194 mem_fragmentable_MB = mem_free * 0.8 / 1024;
195
196 while (mem_fragmentable_MB > 0) {
197 map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
198 MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0);
199 if (map == MAP_FAILED)
200 break;
201
202 entry = malloc(sizeof(struct map_list));
203 if (!entry) {
204 munmap(map, MAP_SIZE);
205 break;
206 }
207 entry->map = map;
208 entry->next = list;
209 list = entry;
210
211 /* Write something (in this case the address of the map) to
212 * ensure that KSM can't merge the mapped pages
213 */
214 for (i = 0; i < MAP_SIZE; i += page_size)
215 *(unsigned long *)(map + i) = (unsigned long)map + i;
216
217 mem_fragmentable_MB -= MAP_SIZE_MB;
218 }
219
220 for (entry = list; entry != NULL; entry = entry->next) {
221 munmap(entry->map, MAP_SIZE);
222 if (!entry->next)
223 break;
224 entry = entry->next;
225 }
226
227 if (check_compaction(mem_free, hugepage_size) == 0)
228 return ksft_exit_pass();
229
230 return ksft_exit_fail();
231}
232

source code of linux/tools/testing/selftests/mm/compaction_test.c